Living under a flight path can raise your blood pressure

An international study is suggesting that night-time noise from aircraft or traffic raises blood pressure even while people are asleep.

The study by researchers from Imperial College London was part of a four-year study exploring the health effects associated with exposure to aircraft noise.

The Hypertension and Exposure to Noise Near Airports (HYENA) project includes studies conducted near major airports in Germany, Greece, Italy, the Netherlands, Sweden and the UK, and involved a total of 5,000 people.

The researchers monitored 140 sleeping volunteers in their homes near Heathrow airport and three other big European airports; the volunteers' blood pressure was measured at 15-minute intervals and then related to the noise recorded in their bedrooms.

The researchers found that the volunteers blood pressure increased after exposure to a noise louder than 35 decibels whether it comes from overhead aircraft or snoring.

Dr. Lars Jarup who led the research says aircraft noise caused an average increase in systolic blood pressure of 6.2 mmHg and an average increase in diastolic blood pressure of 7.4 mmHg; similar increases in blood pressure were seen also for other noise sources such as road traffic.

The researchers say the louder the noise, the greater the increase in blood pressure and for every five decibel increase in aircraft noise at its loudest point, there was an increase of 0.66 mmHg in systolic blood pressure.

In previous research the team had shown that people living for at least five years under a flight path near an international airport are at greater risk of developing high blood pressure than people living in quieter areas.

The two studies suggest that living under a flight path could almost double the risk of hypertension as the researchers calculated that for every extra 10 decibels of aircraft noise the risk of hypertension is increased by 14%.

Why this happens is unclear but the researchers suspect that the brain reacts to noise by pumping up levels of the stress hormone cortisol.

High blood pressure is linked to an increased risk of heart disease, stroke, kidney disease and dementia.

The World Health Organisation defines high blood pressure as being 140/90mmHg or more.

Dr. Jarup says while noise from air traffic can be a source of irritation, the research shows that it can also be damaging for people's health, which is particularly significant when plans to expand international airports are discussed.

The researchers say it is clear that measures need to be taken to reduce noise levels from aircraft, in particular during night-time, in order to protect the health of people living near airports.

They are continuing their research in order to find out whether combined exposure to noise and air pollution increases the risk of heart disease.

The study is reported in the European Heart Journal.